This invention relates to a sighter for calibrating a crossbow sight to align with the groove axis of a crossbow for the purpose of calibrating the crossbow sight. The calibration process of a crossbow scope to align the sight with the crossbow groove axis now requires that several bolts be fired so that the sight can be gradually adjusted to align with a target point that the bolts strike. The crossbow sight can be a physical sight or an optical scope. Crossbow sights and crossbow structures are known to those skilled in the art.